Heater quit... sort of

[cmurf]

Many thanks to wizzer and dfluitt for the fix and the photos, put up with this problem for almost two years because i didnt want to spend 900 on the fix from the dealer. 20 dollars on soldering stuff from radio shack, much more tolerable. I would just add to anyone who is going to try this for the first time that the little tool to remove the old solder was key to this fix. many thanks once again for the money saving fix

[Aggman]

I did this repair sucessfully a few months ago, on the 2004 Highlander fan and temperature controls (automatic version). I found the following to be useful:

1- Test for continuity between each of the 3 conductors in each of the ribbon cables (both the fan speed and the temperature controls have similar ribbon cables prone to the same failure). I used an inexpensive VOM (Volt-Ohm Meter) to do this. The corresponding solder points on the control and mainboard are easy to access. There seemed to be some nonconducting layer of the solder (perhaps flux or an oxide layer) so scrape it a little to get a true reading. In my case only one of the outer filament wires on each control's flat cable read open.

2- Solder a jumper wire between the two corresponding solder points that are open; leave the flat cable in place. It does not matter if the broken filament reconnects with the solder at the control solder point. It is simply in parallel with the jumper wire and does not change the circuit. A needle nose plier is helpful to hold the short jumper wire while soldering.

This avoids unecessary work replacing the 3 filaments of each ribbon cable,
which is left in place and saves you from disassembling the control and motherboard to get at the ribbon cable.


The needle nose plier also turned out to be useful for tightening the small nut that keeps the control from rotating during use and opening the flat cable's circuit. This is worth doing even if there is no problem yet with your control, since it seems inevitable that without a locknut, the control will loosen with usage and torque the flat cable's outermost filament off of the control.

This forum was very helpful in solving this problem. The pictures by Toodle posted in message #233 and #234 were quite useful. The dealer wanted $1100 to repair this problem and $69 just to look at it initially.

[patman1]

THANK YOU!!!!

30 minutes start to finish, works perfectly again.

[walkerspencer]

Originally Posted by wizzer

OK. I solved my porblem. Here is what hapened. The nut that holds the temperature control to thee front panel came loose. The knob and control started to wobble. This stressed the wires on back. Eventually 2 of the 3 wires attaching the temperature control to the cotrol circuit board broke. When the control knob was in certain positions one or both came into contact and the heat would come on.

I went to the dealer and they said "replace the heater contol unit." It costs $ 586.00 plus labor. I bought one from a junkyard for $ 75.00. I removed the bezel which surrounds the whole unit by gently prying it with a couple of screwdrivers. Be very careful not to sccratch the dash. Once that I saw that all connections to the back were electircal (3 plugs) I removed the old one. I opened it up and saw the broken wires. I soldered them, reinstalled it and it works fine now.


Pictures attached.

Anyone know if this fix works for a Tundra as well?

Any word on a recall from Toyota? I can't believe the heat doesn't work on my '05....

[05Moose]

Originally Posted by walkerspencer

Anyone know if this fix works for a Tundra as well?

Any word on a recall from Toyota? I can't believe the heat doesn't work on my '05....

Why not pull the knobs off and see if any of the nuts are loose first. May not be the same unit, but possibly the same problem.

[dankat]

Thanks for the great advice on fixing the heater controls. The heater/air conditioner in my 2005 Highlander has had off and on problems for about a year. Never would have tried to fix it myself without your posts.

[schembfr]

Thanks Wizzer and everyone! Same problem 2004 Highlander. Started with a/c intermittently shutting off while driving and it would work again when I jiggled or moved temp control knob. Got worse and worse until pretty much just steaming hot air blowing at me while a/c on. Tonight, spent 5 minutes- pulled off temp control knob (middle one -just pulls off), and found loose nut on switch. Tightened with 7/16" deep socket wrench and a/c worked perfectly again! I probably do have a loose wire behind there, but at least I know the problem and can take it apart when it stops working again.

I was quoted $800 for this repair by Toyota of Weymouth/ Braintree MA for an entire new heater control unit. At this point, it looks like I would've paid $800 to basically tighten a screw. It would've been me who would've gotten the screw!

[lowerfredrick]

Dude! I want to thank you from the bottom of my heart. I was able to save $900 by seeing your post. My wife thinks I'm a genius, and her Highlander is back to normal. Shame on Toyota for not putting a lock nut or something on the shaft. For $0.05 savings they are costing folks probably hundreds of thousands of dollars. One of the three wire was broken, which my wife soldered back up (her eyes are better). Thank you, thank you, thank you. I'd send you a case of beer.

[lowerfredrick]

I also want to thank 'dfluitt' for his invaluable pictures. It gave me the guts to proceed with this simple fix. Thank you, thank you, thank you. You have no idea how happy I am about saving $900, and not giving it to the folks who did this bad design. Had the rotary knob cicuit board been affixed with a simple screw, or a locknut put on the shaft side, none of this would be a $900 issue for lots of people. It's people like you and 'whizzer' who make this site awesome. Thanks for taking the time to help others.

[ladiestoy]

Forgive me if this has been asked, but where exactly is the screw that you tighten? Is it within the white plastic? I cannot afford to take this to a mechanic and Toyota said it would cost $900
Thanks

[lowerfredrick]

You may have inadvertently pulled out the larger ribbon that connects the two haves of the assembly. I did the same thing. There is a small 'collar' that holds these ribbons in. Lift collar, insert ribbon, press collar back down (both sides), and you should be in business. If you can't get it, take it to a computer repair place. They deal with type of stuff all the time. You're almost there with this fix! Don't give up!

[lowerfredrick]

The 'screw' is actually a nut, accessed from the front of the panel. Pull off the center knob/dial while sitting in the driver's seat. Behind this knob is a nut that holds the shaft into place. I used a 12mm socket, but the fit wasn't perfect, although it did work. After tightening, apply Lock-Tite or nail polish to disallow the nut from working loose again. The loose nut allows the small shaft module to vibrate sufficiently to break off the wires connecting it to the circuit board.

[theraginbull]

Hey All,

This thread is one of the most helpful threads I've encountered on TS. The info and pictures helped me with a step by step of what to do and how to do it.

I have an 03 HL and had the same intermittent heating issues you all described. Tore the dash apart and discovered the tell-tale frayed wires and knew what I had to do. As a side note, how this is issue not a recall issue for Highlanders? It appears to be a systemic issue.

Anyway, while the dash was a part I was looking at the back of the radio unit and saw that I had an open port (this is normally where a CD changer would be plugged in). I got curious about whether or not I could install a direct line for my ipod and boy did I make a find.

The website www.mp3yourcar.com will give you mp3 or ipod hook-up options based on the year, make, and model of your vehicle.

I ordered it and as long as I had the dash apart figured I'd install it before putting everything back together.

The only picture I have, unfortunately, is the picture of the finished product.

The ipod hook-up comes with the proper plug to put into the back of your radio, a small box that you install somewhere in the dash, and the wire that will run out to your ipod.

I attached the small converter box to the dashboard frame using Velcro strips and electrical tape.
I drilled a small hole in the inside bottom corner of the center console.
(note: Remove the rear-seat ash tray on the back side of the center console to have access to drill from both sides of the console wall.)
I then used a fish tape to feed the wire from the back side of the center console, all the way up through the center console (it will pass right by the cup holders) and up into the gaping hole in the dashboard that you'll have while the heater and radio unit are out.

My ipod plays through the radio with CD like quality and charges at the same time. The ipod charges through the radio and there is no splicing or taping of wires required!

Follow the instructions and you'll be good to go.

Good Luck and Enjoy!

[cheese4wiz]

Thanks for the post. Sodered the wires and the heat works again but the a/c seems to be intermittened. It will be cold one minute and then just barely cool the next. Any thoughts

[apogue]

wizzer,
you are my hero. I am a poor soderer and I did this in no time...